1. Field
The present invention relates generally to the effects of scatter radiation on radiation imaging devices, and may be applied, for example, to portal imaging in conjunction with radiation therapy.
2. Description
Some conventional imaging devices can acquire images that represent incident X-ray radiation. For example, amorphous selenium-based imaging devices convert received X-ray radiation to stored electrical charge that represents an intensity distribution of the X-ray radiation. Other imaging devices may include a scintillator layer that receives X-ray radiation and emits light in proportion to the intensity of the received radiation. An array of charge-coupled devices or photodiodes receives the light emitted by the scintillator layer and stores electrical charge in proportion to the intensity of the received light. In either case, the stored electrical charge may be used to generate an image that represents the received X-ray radiation.
Portions of the received radiation may be attenuated by objects disposed between the imaging device and a source of the radiation. Consequently, the received radiation and the acquired image will include areas of different intensities that reflect different compositions of the objects. For example, areas of low radiation intensity may represent bone and areas of high radiation intensity may represent tissue. Images acquired using X-ray radiation may be used to diagnose illness, to plan radiation therapy, to confirm patient positioning prior to therapy, and/or to confirm a shape and intensity distribution of a radiation field prior to therapy.
The foregoing imaging techniques may generate scatter radiation. Some of this scatter radiation may be represented in the images acquired thereby. The scatter radiation may reduce the intensity gradients (i.e. contrast) between image areas that represent different objects, and/or reduce the signal-to-noise ratio of the acquired images. Accordingly, it would be beneficial to provide improved image quality by addressing the issue of scatter radiation.